With jellybean I have never flashed a single ROM on my nexus 7. Its not even rooted or boot loader unlocked. Stock is almost perfect in terms of speed and UI. No need. Perhaps a bit more customisations but I can do most of that with some useful tools/apps from the play store.

On the galaxy nexus, I did not flash nothing at first but then I just tried a few ROMs just for fun. Most were quite cool. Some nice additions. Blackbean and rasbean jelly had some nice touches. But I had problems with battery life on one and a reboot issue on another. So I been on stock ever since. Unrooted too...just to keep my sky go working sweet!

On my old devices however, such as the galaxy note and Asus transformer, I used to flash every now and then. Not as crazy but perhaps every few weeks. Once I found something I liked I usually stuck with it.

Edit...I mean stock 4.1 on the galaxy nexus that is. Don't even go there with 4.2. Sad story for me.

I flashed about once a week for awhile and them after seeing all the cluster 'f' of misc. bugs (every ROM had at least one annoying issue) I would then switch back and forth between stock and CM to see where CM was going since over a few years, it became apparent that CM was always the least buggy. I'm on CM10.1 12/23 now, and although still a few issues (sigh), battery drain is my ultimate necessity. Stock ROM battery drain sucks.

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